There have been a growing interest in and active research and development of cooling devices or heat exchangers applied to electrical and electronic appliances. Under the circumstances, the need to precisely and easily measure or calculate heat dissipation of a heat dissipating element incorporated in the cooling device or the heat exchanger is continuously increasing in the field of quality control, performance test and the like.
A conventional method for measuring the heat dissipation of an object (heating element) is to measure a variation in heat quantity of a heat carrying fluid (or secondary fluid), e.g., water or air, which enters and leaves a vessel accommodating the object. That is, when the heat dissipation is measured in accordance with the conventional method, a heating element is disposed in a vessel or a passage through which the heat carrying fluid flows to absorb heat from the heating element. Then, the heat carrying fluid's thermophysical properties including a temperature change owing to heat transfer between the heat carrying fluid and the heating element, specific heat, flow rate and the like are measured, and the variation in heat quantity (Qv) of the heat carrying fluid is obtained by using the following formula:Qv=mf×c×(T2−T1)  Eq. 1where mf is a mass flow rate (a product of volumetric flow rate and density); c is a specific heat; T1 is an inflow temperature of the heat carrying fluid; and T2 is an outflow temperature of the heat carrying fluid.
However, determining the heat carrying fluid's thermophysical properties is very difficult especially when the amount of the heat dissipation is very little. Further, since the temperature of the heat carrying fluid is higher (or lower) than that of the surroundings of the vessel, the heat carrying fluid loses heat to (or absorbs heat from) the surroundings. Although the vessel or the passage may be insulated in an attempt to prevent this heat loss (or heat absorption) problem, the heat loss (or absorption) cannot be completely prevented. Thus, it is inevitable that the heat quantity variation as calculated above includes a heat quantity variation owing to the heat loss to (or heat absorption from) the surroundings as well as a heat quantity variation owing to the heat transfer between the heat carrying fluid and the heating element.
As described above, the conventional heat dissipation measuring method relies on the heat carrying fluid's thermophysical properties, which are measured with difficulty, and which are susceptible to an unavoidable heat loss the amount of which cannot be precisely measured. Accordingly, the conventional method presents such drawbacks of requiring considerable time, efforts and costs, necessitating complex equipments and methods for measuring the heat carrying fluid's thermophysical properties, and resulting in inaccurate measurement results.